The referenced applications disclose simple PIR motion sensors with low false alarm rates and minimal processing requirements that are capable of discriminating smaller moving targets, e.g., animals, from larger targets such as humans, so that an alarm will be activated only in the presence of unauthorized humans, not pets.
The present invention critically recognizes that particularly with respect to ceiling-mounted sensors, owing to the use of positive and negative detector elements, it is possible for signals from objects to be monitored to cancel along some lines of bearing. In other words, the present invention recognizes that ceiling-mounted detectors inherently have longer detection ranges along some lines of bearing and shorter detection ranges along other lines of bearing. As understood herein, it is desirable to provide a single ceiling-mounted detector that has relatively uniform detection capability along all lines of bearing.